Electric discharge device



July 23, 1935. F. ABSHAGEN ELECTRIC DISCHARGE DEVICE Filed Jan. 2, 1932 ATTORNEY .ing processes.

charge device .is'filled with a gas the spectrum of I Patented July 23, 1935 PATENT OFFICE 2,009,215 ELECTRIC DISCHARGE DEVICE Frani Abshagen,

General New York Berlin, Germany, Electric Company,

assignor to a corporation '0! Application January 2, 1932, Serial No. 584,544

Germany January 1 Claim- (Cl. 176-422) The present invention relates to electric discharge devices generally and more particularly the invention relates to such devices useful as a dark room lamp in the developing processes of the photographic art.

It is now known in the art that photographic developing emulsions are least sensitive to green light and that light of this wave length may be used in apho-tographic dark room at sufiicient intensity to render visibility to the developing process without injuriously afiecting the photographic films and plates being developed, this being true even in the case of panchromatic films and plates. The object of this invention is to provide a light source for a photographic dark room. Another object of the invention is to provide a light source rich in light within the spectral range least harmful to photographic developing emulsions. A further object of the invention is to provide such a light source of great efiiciency and of great simplicity in structure and in operation. Still further objects and advantages attaching tothe device and to its use and operation will be aparent to those skilled in the art from the following particular description and from the appended claim.

In accordance with these objects the invention comprises an electric discharge device of the negative glow type having a body of green fluorescent material located in the path of the light rays emanating from the gaseous filling in said device. The green fluorescent body transmits the green light rays emanating from. said gaseous atmosphere and changes into green light the visible and invisible light rays of shorter wave length than the green light, in particular the blue, violet and ultra violet rays, emanating from said. gaseous atmosphere and indeed to light spectral range corresponding to that most suitable for use in connection with photographic develop- The container of the electric diswhich is relativelystrong in green and weak in light rays of other wave lengths. rays, other than the green rays, may be out off by a green filter and for this purpose the container itself may of a green glass such as those disclosed in the patent to Taylor, #l,5"l2 ,6 25,'issued February 9, 1926, or said container may be of a clear glass having a green filter applied thereto. It the container of the device is filled with a gas, such as argon, krypton, or xenonor a mixture of these gases, which is a comparatively weak light emitter the green filter may be omitted. The strength of the green rays within a The stray light light is increasedif a drop of mercury is present in the container of the device together with an easily ionizable principal gas, the spectrum of mercury vapor being rich in green light rays as is well known in the art. 5 In the drawing accompanying and forming part of this specification several embodiments of the invention are shown in which Fig. 1 is a front elevational view, partly in section, of one embodiment of the invention. 10 Fig. 2 is a similar view of another embodiment of the invention.

Fig. 3 is a similar view of another embodiment of the invention.

Fig. 4 is a similar view of the invention, and

Fig. 5 is a similar view of still another embodiment of the invention. I

Like numbers denote like parts in all the figures. Referring to Fig. 1 the new and novel photo- 20 graphic dark room lamp comprises a container I having the usual threaded socket member 2 attached thereto. Said container I is provided with the usual stem 3 and the ends of coiled wire electrodes 1 and 8 and leads 5 and 6 connected 25 thereto respectively are sealed into pinch-part l of said stem 3, said coiled wire electrodes 1 and 8 are equi-distant from each other at all respective parts thereof. Container I is filled at a low pressure with an easily ionizable gas such as 30 argon, krypton, xenon or a mixture of such gases. Green glass fluorescent body I0 partly surrounds said electrodes I and 8 and is supported in said container I by glass rod 9 fused tothe pinch-part I of said stem]. Said fluorescent body III is of 35 a green fluorescent glass suchas uranium glass or Prasodymium glass. Due to its position with respect to said electrodes 1 and-8 practically all the light rays emitted by the glow discharge covering said electrodes 1 and 8 fall upon fluorescent body III which transmitsthe green colored light and changes the visible and invisible light rays of shorter wave length than said green colored light into visible green colored light. The stray light rays emanating from the glow discharge which are of diiferent. wave length than the green colored light are cut on, if desired by making the container I of a green filter glass such as those disclosed in the patent to Taylor referred to hereinbefore and of normal thickness, or said container I may be of clear glass or normal thickness and have a thin green filter coating thereon such as a translucent green enamel or a green lacquer, or a. Wrattan filter.

The embodiment of the invention shown in l of another embodiment 15 said green 40 a rod l6 fused to Fig. 2 is in all respects similar to that shown in Fig. 1 except the green fluorescent body M and the support rod 9 thereof is omitted and the con tainer itself is a green fluorescent body l2 provided with a green colored filter coating ll such as a translucent green lacquer. If desired the container mayconsist of two layers of glass the inner layer being of a green fluorescent glass and the outer layer of a green filter g In the embodiment shown in Fig. 3 current lead 5 is connected to a ring shaped electrode I! said being supported by support wires connected to a cap shaped electrode I 4, said electrode it being supported in said device by glass said stem 3. Said electrodes l3 and I are surrounded by a light filter I I sup-' ported by members l8 attached to a collar around said stem 3.

gases and a drop of mercury 2|. During the op eration of the device the mercury vaporizes and the spectrum of the light of the mercury vapor predominates the spectrum of the light of the gas filling as is well known in the art. The mercury vapor discharge is on one hand very rich in green is rich in other rays In the embodiment shown in Fig. 5 the device comprises two plate electrodes 22 and 23 which are placed on opposite sides of green glass of normal ifications and changes in 8 plate 25, said plate 25 being coated on both sides with a green fluorescent substance 26 such as zine-sulphide, zinc-silicate, or calcium-tungstate. Said plate 25 may consist of any suitable material such as metal, mica, or glass and is supported by rod 24 sealed into stem 3. Container 21 consists of a thickness or said bulb may consist of clear glass of normal thickness having thereon a translucent green internal coating 28.v

A quantity of mercury may be introduced into the container 21 if desired. Plate 25 itself may be made of a green fluorescent material if desaid stem 3, and current lead 6 is sired While 'I have shown and described five particular embodiments of my invention it will of course be understood that numerous substitutions, mod- 'parture from the broad spirit and scope of the Letters Patent of the United States is:

A photographic dark room lamp emitting a light harmless to photographic developing emulsions comprising a container, negative glow discharge electrodes sealed therein; a gaseous atmosphere therein, the light emitted by said device being rich in green radiations and in light radiations or shorter wave lengt a green fiuorescent body in operative relation to said device to transmit the green light rays and transform the visible and invisible light rays of other wave lengths into visible green light and a filter in operative relation to said device adapted to screen out the light, other than the green light, emitted by said device and by said fluorescent body.

FRANZ ABSHAGEN. 

